Vernon Davis shut out on receptions

Six days after Vernon Davis indicated that the insertion of Colin Kaepernick had freed him to make plays, the previously slumping tight end was, again, largely invisible in Sunday’s 31-21 win over the Saints.

Davis, who had six catches for 83 yards and a touchdown in Kaepernick’s first career start last Monday, didn’t have a catch and was targeted just once. After saying he felt like his “handcuffs” had come off in the game against Chicago, Davis appeared as if his hands were tied on the only pass that came his way: A rocket from Kaepernick clanged off Davis’ hands in the second quarter.

Davis was able to smile when asked about adjusting to the speed of Kaepernick’s throws.

“You really have to develop a relationship with a guy like that, because the velocity of the ball is so much different from (Alex Smith‘s) ball. You really have to get your head turned around faster, and make plays. He’s definitely got a stronger arm.”

Aldon Smith at it again: After his 5.5-sack performance last Monday, outside linebacker Aldon Smith added 1.5 to his total Sunday.

Smith, who leads the NFL with 16.5 sacks, has 30.5 career sacks, which is the second-highest total in league history for a player in his second season. With five regular-season games remaining, Smith trails Hall of Famer Reggie White, who had 31 sacks in his first two seasons.

The 49ers had five sacks against New Orleans, which entered having allowed the sixth fewest in the league.

“Drew Brees does a good job of getting rid of the ball,” Smith said, “but we do a good job of getting pressure on quarterbacks and getting to them.”

Jacobs debuts: For the second time this season, running back Brandon Jacobs was active. For the first time, he actually got onto the field – and onto the stat sheet.

Late in the fourth quarter, Jacobs had a 1-yard run on 2nd-and-18 from the Saints’ 20, his first carry since he was playing for the Giants in last season’s Super Bowl.

With Kendall Hunter‘s status in question because of an ankle injury sustained in the third quarter, Jacobs could be in line for more carries Sunday at St. Louis.

Briefly: The 49ers improved to 10-3 on the road under Jim Harbaugh. … The 49ers had two interception returns for touchdowns for the first time since linebacker Ken Norton returned two picks for scores Oct. 22, 1995. … Since 2011, the 49ers are 20-1-1 when Frank Gore and Hunter combine for at least 20 carries.